1. Field of the Invention
The invention relates to blow molding machines of the type in which tubular parison of plastic material is continually extruded at one station, mold halves for a necked product such as bottle closing around the parison which is severed from the extruder and carried by the mold halves to a blow molding station. At this station a blow pin assembly is lowered against the mold halves to form the neck portion of the product and force compressed air into the parison. The invention is particularly concerned with formation of the neck edge and control of the hot flash thereabove.
2. Description of the Prior Art
U.S. Pat. No. 3,470,582 shows a construction for compacting and trimming necks in blow molded containers. In this construction, the blow pin has a shoulder which enters a cylindrical surface on the mold sections. Inevitably, a slight clearance must exist between this blow pin and surface resulting in a burred or fuzzy neck edge. This must eventually be trimmed and reamed at a separate station, often resulting in the inadvertent deposit of resin particles in the bottle.